A Highly Active Aqueous Olefin Metathesis Catalyst Bearing a Quaternary Ammonium Group

A polar olefin metathesis catalyst that bears a quaternary ammonium group was prepared from commercially available reagents. The electron-withdrawing quaternary ammonium group not only activates the Ru catalyst electronically but at the same time makes the catalyst more hydrophilic. The catalyst can therefore be efficiently used both in traditional media, such as dichloromethane and toluene, as well as in technical-grade alcohols, alcohol-water mixtures and in neat water. Various metathesis reactions, including ring-closing, cross- and enyne metathesis, were conducted in these solvents in the presence of air. In addition, the Ru catalyst can act as an inisurf (initiator and surfactant) molecule, promoting metathesis under heterogeneous aqueous conditions.